OFFSET
1,1
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1046
MATHEMATICA
Collatz[n_] := NestWhileList[If[EvenQ[#], #/2, 3 # + 1] &, n, # > 1 &]; t = {}; Do[If[Length[Select[Collatz[n], OddQ]] == 7, AppendTo[t, n]], {n, 1, 10000, 2}]; t
col7Q[n_]:=Length[Select[NestWhileList[If[EvenQ[#], #/2, 3#+1]&, n, #>1&], OddQ]]==7; Select[ Range[1, 5201, 2], col7Q] (* Harvey P. Dale, Sep 25 2023 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
T. D. Noe, Oct 31 2011
STATUS
approved